RECONSTRUCTION WITH TENODESIS IN AN ADULT FLATFOOT MODEL - A BIOMECHANICAL EVALUATION OF 4 METHODS

Six fresh-frozen adult cadaveric specimens were mounted in an Instron materials testing machine with nse of a cemented intramedullary rod, A ngular relationships between the first metatarsal and the talus were r ecorded with a sonic digitizer, A flatfoot deformity was created by di viding the talonavicular joint capsule (superiorly, medially, and infe riorly), the spring ligament, the anteromedial aspect of the subtalar joint capsule, and the plantar fascia, Angular displacement in the sag ittal and transverse planes was recorded at no load and at 100, 350, a nd 700-newton plantar loads, Each specimen was subjected to four diffe rent reconstructions with tenodesis, and the angular relationship betw een the first metatarsal and the talus was measured at the four levels of load, A reconstruction with use of the peroneus longus tendon was performed by preserving its insertion into the first metatarsal, rerou ting the tendon and passing it from medial to lateral through a calcan eal bone tunnel, and anchoring it to the lateral aspect of the calcane us, A reconstruction with the tibialis anterior tendon was performed b y passing the medial third of the tendon from dorsal to plantar throug h the navicular and from medial to lateral through the calcaneal bone tunnel and securing it to the lateral aspect of the calcaneus, The rec onstruction with the tibialis anterior tendon was repeated with the te ndon graft routed along the medial aspect of the navicular, directly t hrough the calcaneal bone tunnel, The fourth reconstruction was done w ith use of an Achilles tendon allograft, For this procedure, a bone pl ug was secured, with an interference screw, in the medial aspect of th e calcaneal bone tunnel, and the graft was passed from plantar to dors al through the navicular and sewn to itself,The reconstruction,vith th e peroneus longus tendon provided significantly greater correction of the deformity in both the transverse and the sagittal plane at all lev els of load (p < 0.05), except the 700-newton load in the transverse p lane, All reconstructions corrected, at least partially, the deformity at both no load and the 100-newton load. CLINICAL RELEVANCE: The meth ods that are used for reconstruction of a ruptured tibialis posterior tendon do not correct the acquired flatfoot deformity of this conditio n, A supple deformity without osseous deformity should be amenable to soft-tissue reconstruction, Of the four methods that we evaluated for reconstruction of a flatfoot deformity, the one involving use of the p eroneus longus provided the best correction in both the transverse and the sagittal plane, We believe that it has the greatest potential for success in a clinical situation.